Thread cutting mechanism for railway sewing machine



O United States Patent l 13,543,708

[72] Inventor George B. Armstead,Jr. 3,143,987 8/1964 Daniel et al... 112/252 Glastonbury, Connecticut 3,217,680 11/ 1965 Harris et al.. 112/252 [21] Appl. No. 778,210 3,296,986 l/l967 Gansl 1l2/252X [22] Filed Nov. 22,1968 3,421,465 l/1969 Marek et a1 112/252 [45] Patented Primary Examiner-Alfred R Guest [73] Assignee The Merrow Machine Company Hartford, Connection Attorney Bevendge & De Grand] a corporation of Connecticut [54] THREAD CUTTING MECHANISM FOR RAILWAY SEWING MACHINE 6 claims: Drawing Figs. ABSTRACT: A railway sewing apparatus including a sewing Us. machine having a thread chain cutting mechanism mounted ll2/12114 for movement with the sewing machine to trim the thread [51] Int. Cl D05b 65/06 chain at the leading and trailing edges f stationary articles [50] Field of Search 112/7, sewn by the machine The cutting mechanism includes a 121-14, 251129.130 clipper assembly supported above the needle plate of the machine to pass above the top surface of articles sewn on the [56] References Cited machine. A vacuum draws the thread chain up above the sewn UNITED STATES PATENTS articles in position to be engaged and cut by the clipper as- 2,724,352 1l/1955 Gentry et al. 1 l2/121.14 sembly as the machine moves along the articles sewn.

Patented Dec. 1, 1970 r 3,543,708

Sheet 1 012 INVENTOR GEORGE B. ARMSTEAD, JR.

ATTORNEYS Patented Dec. 1, 1970 r Sheet ATTORNEYS.

THREAD CUTTING MEGHANXSM FOR RAILWAY SEWING MACHINE This invention relates to thread cutting mechanism for sewing machines, and more particularly to an improved thread chain cutting mechanism for a railway sewing machine.

Railway sewing machines are commonly used to sew long straight seams such as the seams employed to sew together the relatively short lengths of cloth woven on a loom to form a long, or continuous length of cloth for subsequent processing or other operations. These railway sewing machines employ a conventional commercial sewing machine, such as the well known Merrow overedge sewing machine, mounted on a carriage which is propelled along a railway, or track, at a rate equal to the rate at which the cloth is fed through the machines sewing mechanism so that the cloth being sewn remains stationary. One such railway sewing machine is illustrated generally in U.S. Pat. No. 2,724,352, to Gentry.

To use a railway sewing machine, the carriage and machine are retracted to one end of the railway, and the articles to be sewn, e.g. the ends of the two lengths of cloth to be sewn together, are clamped in superimposed relation on a support surface extending parallel to the railway, with the superimposed ends of cloth projecting into the path of the machine's sewing mechanism. The drive mechanism is then actuated to operate the sewing machine and to propel the carriage along the railway to engage and sew together the stationary superimposed ends of cloth as the machine traverses a fixed path defined by the railway. Since the speed of the carriage along the railway is equal to the feed rate of the sewing machine, there is no tendency to drag or pull the cloth along its support surface. However, the support surface must necessarily be positioned closely adjacent the sewing machine needle plate in order to accurately position and guide the cloth through the sewing station of the machine.

After the machine traverses the railway to complete the sewing operation, the carriage drive is reversed to return the mechanism to the starting position.

Since operation of the railway is automatic, in that it traverses the path and returns without requiring the attention of an operator, it is desirable to have somemeans for automatically trimming the chain of thread from the sewn cloth adjacent the leading and trailing edges of the material. This is particularly important with respect to the trailing edge in that it is desirable to sever the thread chainupon completion of the sewing operation to free the mechanism for its return path to the starting position. However, for various reasons, conventional thread cutting attachments employed on commercial sewing machines have proven unsatisfactory for use with railway sewing machines. For example, the close proximity of the work support surface to the needle plate greatly restricts the room available for a thread cutting attachment. Further, many of the conventional thread cutters are not readily adaptable to a moving machine. Accordingly, it is a primary object of the present invention to provide an improved railway sewing apparatus including an improved thread chain cutting mechanism.

Another object is to provide a thread chain cutting attachment for a railway sewing machine including a clippenype thread cutter positioned above the cloth sewn.

Another object is to provide such a thread cutting mechanism in which the clipper assembly is supported above the needle plate of the sewing machine, and spaced rearwardly therefrom, and in which a suction device is provided intermediate the machine sewing mechanism and the clipper mechanism to draw thread chain upwardly above the sewn cloth in position to be engaged and cut by the clipper mechanism moving with the machine.

in the attainment of the foregoing and other objects, an important feature of the invention resides in providing a suction nozzle rearward of the sewing machine presser foot and spaced vertically thereabove in position to draw thread or thread chain upwardly above the plane of the needle plate. A clipper mechanism including a pair of relatively movable superimposed blades are supported in a horizontal position rearwardly of the suction nozzle, with the cutting blades being disposed transversely of the path of travel of the machine. The clipper blades are spaced above the plane of the needle plate so that cloth sewn on the machine passes beneath the clipper blade. An elongated, narrow, rodlike holddown finger mounted on the sewing machine extends rearwardly from the machine presser foot to resiliently hold the sewn cloth to prevent the cloth from being drawn upwardly into the suction device. However, the narrow holddown finger is ineffective in retaining thread or thread chains so that the thread, both at the leading and trailing edges of the sewn cloth, is automatically cut as the machine moves along the railway.

Other objects and advantages of the invention will become apparent from the following detailed description, taken with the drawings, in which:

FIG. 1 is a fragmentary front elevation view, partially in section, of a railway sewing apparatus embodying the present invention;

FIG. 2 is a fragmentary and elevation view of the apparatus shown in FIG. 1; and

FIG. 3 is a fragmentary top plan view of the device, with parts being broken away to more clearly illustrate the relative position of certain of the parts.

Referring now to the drawings in detail, a railway sewing mechanism embodying the present invention is designated generally by the reference numeral 10 and includes a commercial overedge sewing machine 11 mounted on a railway carriage assembly 12. The railway carriage 12 includes a horizontal platform 13 having a pair of downwardly depending flanges 14, 15 formed thereon one adjacent each side edge of the platform. A pair of axles 16, 17 extend between flanges 14, 15 and are supported thereby for rotation about spaced parallel axes, one adjacent each end of the carriage 12. Axles 16, 17 each have a pair of wheels 18 mounted thereon, one adjacent each end thereof in position to engage and support the carriage for reciprocal movement along a straight line path defined by a pair of horizontal parallel rails 19, 20. The rails 19, 20 each have their upper surface tapered in the form of an inverted V, and the wheels 18 each have a complementary V-shaped groove around their outer periphery, with the V-shaped groove and top surface of the rails cooperating to accurately position the carriage along the straight line path defined by the rails. The shaft 16 has a beveled gear 21 fixed thereon, with gear 21 mating with a driven beveled gear 22 fixed on a drive shaft 23. The drive shaft 23 is rotatably driven by a suitable motor (not shown) to propel the carriage back and forth along the tracks 19, 20.

The sewing machine 11 includes a presser foot 25 which is resiliently urged downwardly by an arm 26 toward the machine needle plate 27 to cooperate with conventional feed dogs (not shown) to feed work material through the machine sewing station, indicated by the needle 28, to be sewn in the conventional manner. Thus, the sewing machine of this apparatus operates in its normal manner to perform the sewing function, with the operation of railway machines differing from stationary machines only in that a seam is formed by the machine traversing the material rather than the material being fed through the machine.

To support the work material in position to be sewn by the moving machine, an elongated angled bracket 30 is supported adjacent the path traversed by the needle plate 27, with the upper surface 31 of angle bracket 30 providing a horizontal support surface for the work material, which support surface is essentially coplanar with the top surface of the needle plate. To form a seam on the device, material to be sewn is positioned on surface 31, with the edges of the work material projecting outwardly therefrom in position to be engaged by the sewing machine feed mechanism as the machine moves along the edge of the bracket 30. The work material is retained in i this position by suitable means such as clamps (not shown) at tially horizontal platform 37 extending rearwardly from the presser foot and spaced above the needle plate 27. An elongated, slender, resilient spring holddown member 38 is rigidly secured, as by welding indicated at 33$, on the upper surface of platform 37. The holddown member, or arm 38, extends toward the rear of the sewing machine in a vertical plane substantially parallel to a vertical plane containing needle 23, with the spring element 38 being spaced slightly to the left of needle 28, as viewed in FIG. 1. Thus, as the machine traverses a piece of work material supported on surface 31, arm 3% will overlie the work material adjacent the sewn edges thereof. Arm 38 is formed to engage the upper surface of the sewn material to resiliently retain the material against substantial vertical movement above the plane of the work support surface 31.

A clipper assembly 40 is mounted in vertically spaced relation to the work support surface defined by the needle plate 27 and angle bracket 30, with the clipper assembly being positioned above resilient arm 3% and rearwardly from the sewing machine presser foot. Clipper assembly 40 includes a lower stationary, horizontally extending, clipper blade 4i having a forwardly extended serrated, or toothed, cutting edge 42, and an upper movable blade 43 similarly having a forwardly extending serrated, or toothed, cutting edge 44. The cutting edges of the clipper blades extend transverse to the path of the sewing machine along the material to be sewn, with the blades being supported in this position by suitable bracket means 45 on the cylindrical housing 46 which houses an eccentric drive member 4'7 for driving the blade 43 for reciprocal movement over the stationary blade 41.

The housing 46 is rigidly supported by a bracket 53 attached, as by welding, to a horizontal arm 48 which, in turn, is adjustably supported by a mounting bracket 49 on a rigid vertical support column 50. Column 50 is rigidly supported by a suitable floor flange 51 mounted on the upper surface of platform 13 behind sewing machine ii. A suitable electric motor 52 is mounted on housing 46 and is operatively connected to the eccentric drive element 47 for driving the clipper assembly.

A suction nozzle assembly 54 is removably supported on housing 46 by an adjustable clamp 55, with the open inlet 56 of the nozzle 54 positioned above and forward of the clipper assembly 4% and rearwardly of the presser foot 25. An elongated flexible suction tube 57 has one end connected, as by clamp 58, to the nozzle assembly 543, and its other end connected to a source of vacuum (not shown).

From the above, it can be seen that, as the sewing machine ll is moved along a straight line path over the rails 19, 20 to sew a straight seam in work material supported on the work support surface 31, the resilient arm holddown element 35% extending rearwardly from the sewing station of the machine will pass above work material sewn on the machine and resiliently urge the material downwardly toward the work support surface. Thus, the holddown arm 38 will effectively prevent the suction from the open inlet 56 of the vacuum nozzle 54% from lifting the work material up into the open inlet. However, since the holddown arm 38 is a relatively'small rod or wire, and is slightly offset laterally from the seam sewn by the sewing machine, this holddown element will be totally ineffective in holding down a chain of stitches (where a chain stitch machine is employed) or sewing thread from the machine against the vacuum from the inlet 56. Thus, at the beginning of a seam in a piece of work material, the excess sewing thread or stitch chain will be drawn upwardly into the vacuum nozzle and retained in this position until the leading edge of the work material passes beneath the clipper assembly to draw the upwardly extending thread into the clipper assembly to be cut. The severed thread will then be drawn oil through the vacuum tube 57, leaving the work material neatly trimmed. Similarly, as the trailing edge of the work piece passes beneath the clipper assembly, the thread chain will be drawn upwardly into the vacuum nozzle and retained until it is drawn into the clipper and cut at the desired distance from the trailing edge of the material.

By mounting the clipper assembly'for vertical adjustment relative to the support surface St, the length of thread chain at the leading and trailing ends of the seam can readily be adjusted. Further, the position of the open inlet es of nozzle 54 can readily be adjusted as necessary to assure that the thread chain to be cut is picked up by the nozzle and retained in position to be drawn into the clipper assembly.

As is clearly seen from FIG. 2, the holddown rod 33 may be spaced vertically above the work support surface during a portion of its length in the vicinity of the suction nozzle to further assure that the thread chain will not be restrained by the holddown assembly.

While I have disclosed and described the preferred embodiment of my invention, 1 wish it understood that I do not intend to be restricted solely thereto, but that I do intend to include all embodiments thereof which would be apparent to one skilled in the art and which come within the spirit and scope of my invention.

I claim:

it. in a railway sewing apparatus including a railway, a carriage movably mounted on said railway, drive means for moving said carriage along a fixed path defined by said railway, and a sewing machine mounted on said carriage for movement therewith, said sewing machine having a stitch-forming mechanism including a needle for forming a continuous chain of stitches at a stitch forming station in said machine to form a scam in a stationary work piece positioned on a work support surface adjacent said railway as the machine moves therealong, a thread chain cutting mechanism comprising, in combination, a vacuum tube connected to a source of reduced pressure and having an open inlet, means supporting said vacuum tube for movement with said machine along said fixed path with said open inlet spaced above said work support surface and rearwardly of said stitch-forming station in position to draw a chain of stitches formed by said stitch-forming mechanism upwardly above said work support surface and into said open inlet, a cutting assembly, means mounting said cutting assembly for movement with said machine along said fixed path, said cutting assembly including a movable cutting blade supported in vertically spaced relation above said support surface and transversely of said fixed path in position to engage and sever thread chains drawn above said work support surface by said vacuum tube, motor means for driving said cutting assembly to move said cutting blade to sever said thread chains, and holddown means mounted on said machine and extending rearwardly from said stitch-forming station beneath-said open inlet and above said work support surface in position to engage the top surface of a workpiece sewn by said machine to prevent the workpiece from being drawn into said open inlet, said holddown means including an elongated resilient member extending generally parallel to said fixed path and laterally offset from a seam sewn by said machine in position to resiliently urge a workpiece passing thereunder downwardly away from said open inlet.

2. In the railway sewing apparatus according to claim 1, the further improvement wherein said cutter assembly is mounted for adjustment relative to said holddown means to vary the length of thread chain left on the leading and trailing edges of a workpiece sewn on the machine.

3. In the railway sewing apparatus according to claim 2, the further improvement wherein said vacuum tube is mounted for adjustment relative to said cutter assembly to vary the position of said open inlet.

41. In the railway'sewing apparatus according to claim 2, the further improvement wherein said cutter assembly and said motor means are mounted on a bracket assembly carried by said carriage, said bracket assembly including means for adjusting the position of said clipper assembly and said motor means.

5. in the railway sewing apparatus according to claim 5, the further improvement wherein said cutter assembly comprises a pair of cooperating, relatively movable blades.

6. In the railway sewing apparatus according to claim 4, the further improvement wherein said cutter assembly comprises cutting teeth formed thereon for engaging and severing said thread chains. 

